Patch antenna and antenna device

The present application is based on PCT filing PCT/JP2022/033526, filed Sep. 7, 2022, which claims priority from Japanese Patent Application No. 2021-153829, filed Sep. 22, 2021, the contents of each are hereby incorporated by reference.

The present disclosure relates to a patch antenna and an antenna device.

PTL1 discloses a patch antenna including a ground conductor and a radiating element that are both formed of plate-shaped members.

[PTL 1] Japanese Patent Application Publication No. 2018-42109

The patch antenna described in PTL 1 is an antenna in which the direction normal to the plate surface of the radiating element is the direction of radiation, and the antenna has a high directivity in this direction of radiation. However, if the area of the plate surface of the ground conductor is reduced in order to downsize the patch antenna, radio waves may be emitted in the direction opposite to the direction of radiation as well, resulting in the reduction in the gain in the direction of radiation.

An example of an object of the present disclosure is to downsize a patch antenna and suppress reduction in the gain in the direction of radiation. Other objects of the present disclosure will become apparent from the present specification given herein.

An aspect of the present disclosure is a patch antenna comprising: a first element; and a second element located so as to face the first element, wherein the first element includes a first main body portion facing the second element, and at least one first bent portion extending from the first main body portion toward the second element, and a wave source is generated between the second element and the first bent portion.

According to an aspect described above of the present disclosure, it is possible to downsize a patch antenna and suppress the reduction in the gain in the direction of radiation.

At least following matters will become apparent from the description of the present specification and the accompanying drawings.

Hereinafter, preferred embodiments of the present disclosure will be described with reference to the drawings. The same or equivalent components, members, and the like illustrated in the drawings are given the same reference numerals, and an overlapping description is omitted as appropriate.

==Patch Antenna==

<<Overview of Patch Antennaof First Embodiment>>

First, an overview of a patch antennaof a first embodiment will be explained with reference to.

is a perspective view of the patch antennaof the first embodiment.is a side view of the patch antennaof the first embodiment, andis a front view of the patch antennaof the first embodiment.

<<Definition of Directions and the Like>>

In the following, as given in, three orthogonal left-handed axes will be defined, and explanations will be given according to the directions along the axes. Note that the coordinate origin of the three orthogonal axes is the center of a radiating element(described later).

A “+X direction” and a “+Y direction” are defined as directions that are parallel to the plate surface of the radiating element(described later) of the patch antennaand are orthogonal to each other. In the patch antennaof the first embodiment illustrated in, the +X direction is also the direction from a feeding portion(described later) of the radiating elementtoward the center of the radiating element. Further, a “+Z direction” is defined as the direction normal to the plate surface of the radiating element. Note that a “−X direction” is defined as the direction opposite to the +X direction. Further, both the +X direction and the −X direction, or either one of the +X direction or the −X direction may be simply referred to as the “X direction”. Further, as in the X direction and the −X direction with respect to the +X direction, the “Y direction” and the “−Y direction” with respect to the +Y direction, and the “Z direction” and the “−Z direction” with respect to the +Z direction are also defined.

Here, the “center” of the radiating elementrefers to the center point, in other words, the geometric center, in the shape of the outer edge of the radiating elementin the front view of the radiating elementviewed in the −Z direction.

Further, the “plate surface” of the radiating elementrefers to a predetermined surface of a plate-shaped member when the radiating element is mainly formed of the plate-shaped member. Here, for example, in the case of the radiating element, which is illustrated inand is constituted by only the plate-shaped member, the predetermined surface is the surface on the +Z direction side of the radiating element(hereinafter may also be referred to as “front surface”). In addition, for example, in the case of a radiating elementE including a radiating element bent portionE (described later), which is illustrated indescribed later, the predetermined surface of the radiating element is the front surface of a radiating element main body portionE (described later), which is formed as a plate-shaped member. Further, when the radiating element is formed of a conductive pattern provided at a substrate, the “plate surface” of the radiating element is the front surface of the substrate, at which the conductive pattern is formed.

The “direction normal to the plate surface” of the radiating elementis, as is apparent from the fact that it is defined as the +Z direction, a direction perpendicular to the plate surface of the radiating element, and is the direction from the surface on the −Z direction side (hereinafter may be referred to as “back surface”) toward the surface on the +Z direction side (front surface). In other words, the “direction normal to the plate surface” of the radiating elementdoes not refer to both the direction from the back surface to the front surface of the radiating elementand the direction from the front surface to the back surface, but refers to the fixed direction.

Further, in the patch antenna, the +Z direction is the direction of radiation, as will be described later. Further, in the patch antenna, the +Z direction is the direction of radiation, as will be described later.

Here, in the figures described below including, directions are given in the figures as reference directions. The reason why they are given as reference directions is that the origin of the coordinates of the three axes orthogonal to one another correctly should be the center of the radiating element, as described above. Accordingly, the directions given in the figures are given for reference only.

<Use and Configuration of Patch Antenna>

The patch antennais a vehicular antenna supporting radio waves in the frequency band used for Vehicle to Everything (V2X: vehicle-to-vehicle communication, road-to-vehicle communication), for example. In an embodiment of the present disclosure, the frequency band used for V2X is, for example, 5.9 GHz band (5.85 GHz to 5.925 GHz), and the target frequency is adjusted to 5.8875 GHz, for example. However, the patch antennamay support Global Navigation Satellite System (GNSS) and Sirius XM (SXM) radio waves, for example, in addition to V2X radio waves. Further, the radio wave communication standards and the frequency bands supported by the patch antennaare not limited to those described above, and may be other communication standards and frequency bands, and the patch antennamay be an antenna other than that of vehicular use. The patch antennais capable of at least one of reception and transmission of radio waves (signals) of the desired frequency band.

In an embodiment of the present disclosure, the term “vehicular” refers to being mountable to a vehicle, and thus it is not limited to one attachable to a vehicle, but also includes one to be brought into a vehicle and used in a vehicle. In addition, it is assumed that the patch antennaof an embodiment of the present disclosure is used for a “vehicle” which is a wheeled vehicle, but it is not limited thereto, but may be used for a movable body such as a flight vehicle including a drone and the like, a probe vehicle, a construction machinery, an agricultural machinery, a vessel, and the like without wheels for example.

The patch antennaincludes a ground conductorand the radiating element.

The ground conductoris a conductive element to which the outer conductor (not illustrated) of a feeder is connected. The ground conductoris located so as to face the radiating element, as illustrated in. In an embodiment of the present disclosure, the ground conductoris located on the −Z direction side relative to the radiating element, and is arranged in parallel thereto. Note that the detailed configuration of the ground conductorwill be described later.

The radiating elementis a conductive element to which an inner conductor (not illustrated) of the feeder is connected. The radiating elementis located so as to face the ground conductor, as illustrated in. In an embodiment of the present disclosure, the radiating elementis located on the +Z direction side relative to the ground conductorand arranged parallel thereto. Note that the ground conductorand the radiating elementare not limited to being parallel to each other. At least one of the ground conductoror the radiating elementmay be arranged to be inclined at a predetermined angle, by being arranged to be rotated about a predetermined axis along the X direction, the Y direction, or the Z direction relative to the other thereof. Furthermore, at least one of the ground conductoror the radiating elementmay have such a curved shape as to be close to each other, or such a curved shape as to be away from each other. Alternatively, at least one of the ground conductorand or the radiating elementmay have such a bent shape as to be close to each other, or may have such a bent shape as to be away from each other.

The radiating elementis formed of a metal plate-shaped member (metal plate) in a substantially quadrilateral shape in an embodiment of the present disclosure, as illustrated in. Here, the term “substantially quadrilateral shape” means a shape consisting of four sides including a square or a rectangle, for example, and at least part of corners thereof may be cut away obliquely relative to a side thereof, for example. Further, in the “substantially quadrilateral” shape, a recess (recessed portion) or a protrusion (protruding portion) may be provided at part of sides thereof. Note that the shape of the radiating elementA is not limited to a substantially quadrilateral shape, but may be a circular shape, an elliptic shape, or the like, for example. That is, the radiating elementA may have any shape as long as it can perform at least one of reception or transmission of signals (radio waves) of the desired frequency band.

The radiating elementincludes a feeding portionas illustrated in. The feeding portionis a portion including a feeding point at which the radiating elementis electrically connected to a feeder not illustrated. The radiating elementof an embodiment of the present disclosure employs a configuration in which one feeding pointis provided, that is, a single-feed system. The radiating elementis configured so as to be able to perform at least one of transmission or reception of radio waves of linearly polarized waves. However, the radiating elementmay employ a quadruple-feed system or a double-feed system so as to be able to perform at least one of transmission or reception of radio waves of desired polarization, for example. Further, the radiating elementmay also support radio waves of the circularly polarized waves, without being limited to radio waves of the linearly polarized waves such as vertically polarized waves and horizontally polarized waves.

Further, the radiating elementincludes an inner conductor connection portionto which the inner conductor of the feeder (not illustrated) is connected. The inner conductor connectionis provided at the back surface of the radiating element, as illustrated in.

In an embodiment of the present disclosure, the plate surface of the radiating elementis arranged perpendicular to the horizontal plane. Here, the horizontal plane refers to a plane perpendicular to the direction of gravity.

In addition, out of the two the elements of the ground conductor and the radiating element, the element on the side opposite to the direction of radiation of the patch antenna may be referred to as “first element,” and the element on the side of the direction of radiation of the patch antenna may be referred to as “second element”. In the patch antennaof an embodiment of the present disclosure, the ground conductoris the first element, and the radiating elementis the second element. In addition, both the first element and the second element may be simply referred to as “element”. Further, when giving a common explanation of the first element and the second element, either one the first element or the second element may be simply referred to as “element”.

Next, before explaining the characteristics of the configuration of the patch antennaof an embodiment of the present disclosure, the patch antennaA as a comparative example will be explained.

is a perspective view of the patch antennaA of a comparative example, andis a side view of the patch antennaA of a comparative example.

As illustrated in, in the patch antennaA of a comparative example, both of the ground conductorA and the radiating elementA are formed of metal plate-shaped members (metal plates). Further, in the front view of the patch antennaA viewed in the −Z direction, the ground conductorA is configured to have the area of the plate surface larger than that of the radiating elementA.

The patch antennaA, which includes the ground conductorA and the radiating elementA illustrated in, has the direction of radiation in the +Z direction (the direction normal to the plate surface of the radiating elementA), and has a high directivity in this direction of radiation.

Due to a request to downsize the patch antennaA, as given by the dotted line with an arrow in, a configuration may be such that the area of the plate surface of the ground conductorA is reduced such that the ground conductorA has the same size as that of the radiating elementA, for example. In this case, as given by the dashed-dotted arrow in, radio waves are radiated also to the side opposite to the direction of radiation, and the gain in the direction of radiation may decrease.

Thus, in the patch antennaof an embodiment of the present disclosure, the shape of the ground conductoris set different from that of the patch antennaA of a comparative example, as illustrated indescribed above. This makes it possible to downsize the patch antennaand suppress the reduction in the gain in the direction of radiation.

<<Characteristics of Patch Antennain First Embodiment>>

The ground conductorincludes the ground conductor main body portionand the ground conductor bent portions, as illustrated in.

The ground conductor main body portionis part of the ground conductorthat is formed as a metal plate-shaped member (metal plate). The ground conductor main body portionincludes an outer conductor connection portionto which the outer conductor (not illustrated) of the feeder is connected. The outer conductor connection portionis provided at the back surface of the ground conductor main body portion, as illustrated in.

Each of the ground conductor bent portionsis a part extending from the ground conductor main body portion. In an embodiment of the present disclosure, such a ground conductor bent portionis formed by bending from the end part of the ground conductor main body portionformed of a metal plate. However, the ground conductor bent portionmay be a metal plate separate from the ground conductor main body portion, and be connected (joined) so as to extend from the end part of the ground conductor main body portion.

Note that a configuration may be such that each of the ground conductor main body portionand the ground conductor bent portionis formed of the conductive pattern provided at the substrate without being formed of a metal plate, and the ground conductor main body portionand the ground conductor bent portionare electrically connected. Alternatively, a configuration may be such that the ground conductor main body portionis formed of the conductive pattern provided at the substrate, the ground conductor bent portionis formed of a metal plate, and the ground conductor main body portionand the ground conductor bent portionare electrically connected. Further alternatively, a configuration may be such that the ground conductor main body portionis formed of a metal plate, the ground conductor bent portionis formed of the conductive pattern provided at the substrate, and the ground conductor main body portionand the ground conductor bent portionare electrically connected. The substrate may be a dielectric substrate such as a printed circuit board and the like, or a substrate made of resin and the like.

When the ground conductor main body portionand the ground conductor bent portionare formed of the conductive patterns provided at the substrate made of resin and the like, it is possible to use Molded Interconnect Device (MID) technology capable of forming a conductive pattern at a resin having a complex three-dimensional shape. For example, a configuration may be such that the conductive pattern is formed, using MID technology, at the resin having such shapes as the ground conductor main body portionand the ground conductor bent portionillustrated in, or the ground conductor bent portionis formed, using MID technology, at a casing made of resin and the like, and is electrically connected to the ground conductor main body portionthat is separate therefrom.

Furthermore, when the ground conductor main body portionand the ground conductor bent portionare formed of the conductive patterns provided at the substrate, the ground conductor main body portionand the ground conductor bent portionmay be integrally formed of a flexible substrate.

In the patch antennaof an embodiment of the present disclosure, the ground conductor bent portionsare respectively provided at two ends in the X direction of the ground conductor main body portion, as illustrated in. That is, the patch antennaof an embodiment of the present disclosure includes two ground conductor bent portions. Then, the two ground conductor bent portionsare located so as to face each other through the ground conductor main body portiontherebetween. However, the ground conductor bent portionmay be provided at only one of the two ends in the X direction of the ground conductor main body portion(the end part on the +X direction side or the end part on the −X direction side). Further, the ground conductor bent portionmay be provided at each of two ends in the Y direction of the ground conductor main body portion, or may be provided at each of two ends in the X direction of the ground conductor main body portionas well as at each of two ends in the Y direction of the ground conductor main body portion. Furthermore, the patch antennamay have three or more ground conductor bent portions.

Further, in the patch antennaof an embodiment of the present disclosure, each of the ground conductor bent portionsextends so as to stand upright from the ground conductor main body portion, as illustrated in. That is, each ground conductor bent portionextends at an inclination angle of 90° with respect to the plate surface of the ground conductor main body portion. However, the inclination angle of the ground conductor bent portionwith respect to the plate surface of the ground conductor main body portionmay be an obtuse angle or an acute angle.

Here, the inclination angle of the ground conductor bent portionwith respect to the plate surface of the ground conductor main body portionrefers to an angle between the plate surface of the ground conductor main body portionand the surface of the ground conductor bent portionon the ground conductor main body portionside. Accordingly, when the inclination angle of the ground conductor bent portionwith respect to the plate surface of the ground conductor main body portionis an obtuse angle, the ground conductor bent portionis inclined to the side opposite to (to the outer side relative to) the center of the ground conductor main body portion. Further, when the inclination angle of the ground conductor bent portionwith respect to the plate surface of the ground conductor main body portionis an acute angle, the ground conductor bent portionis inclined toward the center (to the inner side) of the ground conductor main body portion.

However, the two ground conductor bent portionsrespectively provided at two ends in the X direction of the ground conductor main body portionmay extend so as to form different inclination angles, respectively, with respect to the ground conductor main body portion. For example, of the two ground conductor bent portions, the ground conductor bent portionon the +X direction side may extend to form an obtuse inclination angle with respect to the ground conductor main body portion, and the ground conductor bent portionon the −X direction side may extend to form an acute inclination angle with respect to the ground conductor main body portion.